FE > Semester 1 > Applied Chemistry 1

Marks : 06

Years : MAY 2016

DOLOMITE BRICKS

Preparation:

They are made by mixing calcined dolomite (CaO + MgO) with equimolar proportion of silica as binding material. They are fixed at $1500^oC$ for about 24 hours

Properties:

Advantages:They can withstand a load of $3.5 kg/cm2 \text { at } 1650^o C$.’they are not much resistant to thermal variations.

Limitations:Less strong, more porous and have more softness and shrinkage.

Uses:

• Open-hearth furnaces

• Repair works

• Electric furnace lining, Bassemer converter, ladle-lining etc.

• Cheap substitute for magnesite bricks.

SILICON CARBIDE

Preparation:

They are made from sand and coke which are properly mixed and saw dust and a little salt are added to it.Mixture is then fired at $1500^oC$ in an electric furnace. After the further processes, the mixture is then finally shaped, dried and fired at a temperature of $2000^oC.$

$ SiO2 + 3C \rightarrow SiC + 2CO$

Properties:

Superior strength, high density, high abrasion and chemical resistance, high thermal conductivity and low thermal expansion.

Uses:

• Coke ovens

• Muffle furnaces and floor of heat treatment furnace

• Heating element in the form of rods and bars etc.